I'll second jostby's suggestion about cracking them all loose a little bit etc. The same logic applies when re-torquing the triples. You have to do it in steps 'cuz the first one you tighten will always loosen when you get up on the second, etc...
You might know all this already but ...
No one mentioned an impact so I will.
If no air impact every shadetree mechanic oughta have a hand impact. The hit with a hammer type. The quick snap turn of the hammer blow will crack stuff loose much easier than a slow steady pressure from a wrench.
But before hitting with an impact do as others have suggested and apply a good amount of heat and penetrating oil. In addition to expanding the triple, the heat seems to help the pen oil suck in too. Let 'em soak for a good while before a whack with the impact.
As far as a MC for the woods... here are a couple things I found with my '05 MC 250. I'm an old MX'er (real old) and kind of a noob to this real tight enduro stuff so it may not necessarily apply at whatever your skill level might be.
- The "hit" was crazy. The first thing I did after firing 'er up was loop it in the back yard testing "loftability."
I put on a 12oz. flywheel weight, a G2 throttle with the "slow" cam, went with Pobits recommended jetting for smooth power. 178 main, 42 pilot, CCK needle clip 3. My buddy with an '04 EC 250 still thinks my MC has "angry" power delivery but I think it's fine now.
-The suspension was way stiff but I see you are going to take care of that. Good move. Those Ohlins should be sweet.